Proper Hydration for Exercise -Water or Sports Drinks

What and when athletes drink depends upon exercise duration and intensity
Water is the most essential ingredient to a healthy life.
Water has many important functions in the body including:

Transportation of nutrients / elimination of waste products.

Lubricating joints and tissues.

Temperature regulation through sweating.

Facilitating digestion.

Importance of Water During Exercise
Proper hydration is especially important during exercise. Adequate fluid intake
for athletes is essential to comfort, performance and safety. The longer and
more intensely you exercise, the more important it is to drink the right kind of fluids.

Athletes need to stay hydrated for optimal performance. Studies have found that
a loss of two or more percent of one's body weight due to sweating is linked to
a drop in blood volume. When this occurs, the heart works harder to move blood
through the bloodstream. This can also cause muscle cramps, dizziness and
fatigue and even
heat illness including:

Water Intoxication, although rare, is the risk of drinking too much
water and suffering from hyponatremia or water intoxication. Clearly,
drinking the right amount of the right fluids is critical for
performance and safety while exercising.

Adequate fluid intake for fitness training
Because there is wide variability in sweat rates, losses and hydration
levels of individuals, it is nearly impossible to provide specific
recommendations or guidelines about the type or amount of fluids
individuals should consume. Finding the right amount of fluid
to drink depends upon a variety of individual factors including the
length and intensity of exercise and other individual differences.
There are, however, two simple methods of estimating adequate hydration:

Temperature:
Exercising in the heat
increases you fluid losses through sweating and
exercise in the cold
can impair you ability to recognize fluid losses and increase fluid lost through
respiration. In both cases it is important to hydrate.

Sweating: Some athletes sweat more than others.
If you sweat a lot you are at greater risk for dehydration. Again,
weigh yourself before and after exercise to judge sweat loss.

Exercise Duration and Intensity: Exercising for hours
(endurance sports) means you need to drink more and more frequently
to avoid dehydration.

According to the Institute of Medicine the need for carbohydrate and electrolytes
replacement during exercise depends on exercise intensity, duration, weather and
individual differences in sweat rates. [They write, "Fluid replacement
beverages might contain ~20–30 meqILj1 sodium (chloride as the anion),
~2–5 meqILj1 potassium and ~5–10% carbohydrate."] Sodium and
potassium are to help replace sweat electrolyte losses, and sodium also helps
to stimulate thirst. Carbohydrate provides energy for exercise over 60-90 minutes.
This can also be provided through energy gels, bars, and other foods.

What about Sports Drinks?
Sports drinks can be helpful to athletes who are exercising at a high intensity
for 60 minutes or more. Fluids supplying 60 to 100 calories per 8 ounces helps
to supply the needed calories required for continuous performance. It's really
not necessary to replace losses of sodium, potassium and other electrolytes during
exercise since you're unlikely to deplete your body's stores of these minerals during
normal training. If, however, you find yourself exercising in extreme conditions
over 3 or 5 hours (a marathon, Ironman or ultramarathon, for example) you may likely
want to add a complex sports drink with electrolytes.

General guidelines for fluid needs during exercise
While specific fluid recommendations aren't possible due to individual variability,
most athletes can use the following guidelines as a starting point, and modify
their fluid needs accordingly.

Hydration Before Exercise

Drink about 15-20 fl oz, 2-3 hours before exercise

Drink 8-10 fl oz 10-15 min before exercise

Hydration During Exercise

Drink 8-10 fl oz every 10-15 min during exercise

If exercising longer than 90 minutes, drink 8-10 fl oz of a sports drink
(with no more than 8 percent carbohydrate) every 15 - 30 minutes.

Hydration After Exercise

Weigh yourself before and after exercise and replace fluid losses.

Drink 20-24 fl oz water for every 1 lb lost.

Consume a 4:1 ratio of carbohydrate to protein
(four grams of carbohydrate for every one gram of protein) within the 2 hours after
exercise to replenish glycogen stores. Eating more protein than that, however,
has a negative impact because it slows rehydration and glycogen replenishment.)